Question

a bus tarvels a distance of 120 km with a speed of 40 km /h and returns with a speed of 30 km/h.calculate the average speed for the entire journey .
​

Answer 1

Answer:

$34 \frac{2}{7} \: km/h$

Explanation:

If the bus covers a distance of 120 km at speed of 40 km/h.

Time taken:

$\frac{120 \: km}{40 \: km/h}$

$= 3 \: h$

Now its covers again 120 km because ut covers the same path when its return but its speed now is 30 km/h.

Time Taken:

$\frac{120 \: km}{30 \: km/h}$

$= 4 \: h$

As its covers 120 km distance two times, total distance that is covered in the entire journey of bus will be:

$120 \: km + 120 \: km$

$= 240 \: km$

Now total time taken will be:

$3 \: h + 4h$

$= 7h$

Hence, average speed:

$\frac{240 \: km}{7h}$

$= 34 \frac{2}{7} \: km/h$